Jeff Greason, Chairman of the Tau Zero Foundation (formerly of X-Cor, formerly of Rotary Rocket) is talking about Electric Sky: A Long-Range Wireless Power Transmission System Enabling Orbital Launch Vehicles, with Terrestrial Commerical Applications
Questions Driving Electric Sky"
* Is there any way to bring the cost of a passenger ticket to orbit below $10,000?
* Is there any technology which would allow for high speed point-to-point transport which is both faster and cheaper than subsonic aviation?
* Is there one technology that might do both things?
(Jeff is speaking as an employee of Electric Sky, I think, not as chairperson of Tau Zero)
The Promise of Beams
* Size and cost of vehicles driven by energy storage
* Mature operating cost driven by the price of energy
* If you can beam the power to the vehicle, then
- The energy is massless
- Electricity costs about half as much as fuel
- Electricity-to-work conversion is 2-3 times more efficient than fuel-to-work
Table showing different wavelengths, cost per watt, area of transmitter, and receiver. UHF is super cheap and the receivers are efficient, but the area is HUGE.
There are other practical "beam like" solutions to Maxwell's equations!
A class of Airy solutions in particular has relevance for power beams (Chremmos 2011)
Tight focus a long way from the transmitter AND the beam in the middle is diffuse, which greatly reduces worries about accidental exposure.
Here's a picture of the slide That's a real picture of a real laser.
Same thing in the RF domain.
Next slide: 915 MHz, 740km transmission (i.e. satellite).
Following slide: 915 MHz, 125 km transmission. Sparse array for launch vehicle first stage, 40% of power in 12m radius.
(Ed: Holy shit this is exciting!)
21st century propulsion
100 years ago, people weren't sure what to do with electricity. "Light without smoke"
Question about steering the beam.
You have to steer the beam in all three axes!
(Ed: seems similar to MIMO beamforming)
Dave Weinshenker asked about what he can say about their transmitter array.
Jeff: "It's a very sparse array, but that's all I can say, because not everything has been filed in a patent yet"
Question about power source for a launcher.
A: "It's in the 100 megawatt class."
Question about space-based solar power, which made Jeff giggle.
Jeff: "I don't think anyone else is working on this technique. I think there will be challenges to adapt it to space-based solar."
Question about how far you can place the focus. "Can you place a spot on the moon from the earth?"
A: "I haven't simulated yet". Looking at applications nearer to Earth "unless somebody pays me."
Question about millimeter and shorter wavelengths.
Jeff: very hard to do anything at the receiver with those wavelengths other than make something hot.